In a bowl combine Maseca and water and knead until soft. It should make a nice dough that doesn´t stick to your fingers. Cover with a cloth and rest for 5 minutes.
Heat a skillet or a griddle over medium high heat. Take portions of the dough and flatten them to form medium sized tortillas. Cook them in the preheated griddle, turning them after 3-4 minutes. Keep them wrapped with a kitchen towel.
Heat the oil in a wok over high heat. When very hot add the beef and stir fry, stirring constantly. In quick succession add the garlic, onion, scallions, aji amarillo and tomato. Continue stir frying for a couple minutes.
Add red vinegar and soy sauce, stir, and taste for seasoning.
Serve inside the tortillas, sprinkled with cilantro and more scallions.
Recipe by PERU DELIGHTS at https://perudelights.com/lomo-saltado-tacos-mexican-peruvian-fusion/